Infrared Analysis: Definition

What Is Infrared Analysis?

Infrared analysis, also called infrared thermography or thermal imaging analysis, captures the heat emitted by a surface and converts it into a visual map of temperature distribution. Every object above absolute zero emits infrared radiation proportional to its temperature, so a thermal camera reveals hot spots invisible to the naked eye.

In industrial maintenance, those hot spots are early warning signs. An overloaded circuit generates resistive heat. A failing bearing generates friction heat. A blocked pipe creates a temperature differential. Infrared analysis makes these signatures visible so maintenance teams can act before equipment fails.

Because the camera never touches the asset, inspections can be performed safely on live electrical equipment, rotating machinery, and pressurized systems that cannot be shut down for contact-based inspection.

How Infrared Analysis Works

Thermal cameras detect infrared radiation in the 7 to 14 micrometer wavelength range. A sensor array converts incoming radiation into an electronic signal, which is processed into a thermogram: a false-color image where colors represent temperature levels.

Hot spots appear as bright reds and yellows. Cool areas appear as blues and purples. The temperature scale is calibrated to the expected operating range of the equipment being inspected, making deviations immediately visible.

The thermogram is compared against a baseline image of the same equipment taken under normal operating conditions. A significant temperature rise above baseline, or a pattern inconsistent with normal heat distribution, indicates a developing fault. The severity classification depends on the delta T: the temperature difference between the anomaly and a reference point.

Delta T Severity Classification

What Infrared Analysis Detects

Infrared analysis is effective across electrical, mechanical, and process systems. The range of detectable faults is broad because heat is a byproduct of nearly every failure mode.

Infrared Analysis vs. Other Condition Monitoring Methods

Infrared analysis is one tool in a broader condition monitoring toolkit. Its strength is detecting heat-related faults that other methods cannot. Understanding when to use it versus alternatives helps teams allocate inspection resources effectively.

For asset health monitoring programs, infrared analysis and vibration analysis are commonly deployed together. Vibration analysis catches mechanical degradation in rotating equipment; infrared analysis covers the electrical and thermal side of the same machines.

How to Perform an Infrared Inspection

A structured inspection process ensures that results are repeatable, comparable over time, and actionable. The following steps apply to both route-based periodic inspections and targeted surveys of specific equipment.

1. Define the Scope and Baseline

Identify which assets will be inspected and the operating load at which they should be running during the survey. Infrared analysis is most effective when equipment is under at least 40 percent of rated load, as faults often do not generate significant heat at low loads. Establish baseline thermograms for each asset during normal operation.

2. Select and Calibrate Equipment

Choose a thermal camera with resolution and sensitivity appropriate for the inspection distance and expected temperature range. Set the correct emissivity value for the surface being measured. A metallic surface has a different emissivity than painted steel or rubber, and using the wrong value produces inaccurate absolute temperature readings.

3. Perform the Survey

Inspect equipment from a consistent distance and angle. Follow the defined inspection route to ensure no assets are missed. Capture thermograms of all critical points and note operating conditions at the time of the survey. For electrical equipment, inspect all phases and compare phase-to-phase temperatures, as imbalance between phases is a key diagnostic indicator.

4. Analyze and Classify Findings

Compare thermograms to baseline images and calculate delta T for each anomaly. Classify severity using the delta T table. Photograph each finding with both the thermal image and a visible-light image of the same location to aid work order creation and repair verification.

5. Report and Act

Create a failure analysis report summarizing findings, severity classifications, and recommended actions. Assign work orders for each finding according to priority. Retain thermograms as part of the asset maintenance history for trend analysis over time.

Infrared Analysis in Maintenance Programs

Infrared analysis fits within condition-based maintenance and predictive maintenance frameworks. Instead of maintaining equipment on a fixed calendar schedule, teams inspect it at defined intervals and only intervene when the data indicates a developing fault.

This approach reduces unnecessary preventive maintenance activities, extends component life, and eliminates emergency failures that would otherwise result from undetected electrical or thermal problems.

Integration with Continuous Monitoring

Periodic handheld thermography surveys are the most common deployment model. A technician walks the facility with a thermal camera on a defined route, typically quarterly or annually for electrical systems and more frequently for high-criticality rotating equipment.

Fixed thermal cameras installed at critical points provide continuous monitoring. These are used on high-value assets where periodic surveys introduce too much risk between inspection intervals. Fixed cameras feed data into condition monitoring platforms that alert maintenance teams when temperature thresholds are exceeded.

Industries Where Infrared Analysis Is Most Valuable

Manufacturing: Electrical distribution panels, motor control centers, and conveyor drives are prime targets. Manufacturing facilities depend on continuous electrical supply, making early detection of panel faults a high-value activity.

Process industries: Refineries, chemical plants, and power generation facilities use infrared analysis to inspect refractory lining, heat exchangers, rotating equipment, and high-voltage electrical systems.

Food and beverage: Thermal imaging identifies failing motors and overloaded refrigeration compressors, where thermal faults can lead to both production loss and product spoilage.

Data centers: Infrared analysis of electrical panels, UPS systems, and server room cooling is standard practice to prevent thermal runaway and unplanned outages.

Infrared Analysis and Reliability Programs

Organizations running formal reliability programs use infrared analysis data to track fault trends over time. A bearing that runs 5°C above baseline one month and 12°C above baseline the next month is deteriorating, and the rate of change allows the maintenance team to project remaining useful life and schedule replacement during a planned outage.

This connects directly to failure analysis workflows: thermographic findings feed into root cause investigations and maintenance strategy reviews, helping teams decide whether to repair, redesign, or change operating parameters.

The Bottom Line

Infrared analysis is one of the most versatile and cost-effective tools in the condition monitoring toolkit. It can be applied to electrical systems, rotating equipment, building envelopes, and process piping with the same instrument and set of thermographic principles, making it a practical first line of detection for a wide range of asset types in a single survey.

The value of infrared analysis compounds when findings are trended over time. A thermal anomaly on a motor terminal block that is 10°C above baseline today and 25°C above baseline three months later is deteriorating and heading toward failure. Organizations that use thermography as part of a structured condition monitoring program, retaining images and comparing them systematically, extract significantly more predictive value from each survey than those that use it for one-time spot checks.

Frequently Asked Questions